This invention concerns shift gates on motor vehicles. More particularly, a shift gate is provided that incorporates apparatus enabling a directional control lever to be trapped in a neutral position in a positive manner so as to prevent movement of the control lever without active released by the machine operator.
Shift gates are well known in the prior art. The gate itself is usually a plate provided with a variety of paths through which a control lever may be moved. Often the lever is provided with detented positions that require some input force on the control lever to disengage the lever from the detented position. On more sophisticated shift gates it is common to see a positive lockout device that is provided to prevent the inadvertent movement of a control lever into a lesser used or normally not used gear such as reverse gear on an automobile. These lockouts often are automatically engaged and manually disengaged.
In the construction equipment vehicle field, it is common to see a flip-over type neutral restraining device designed to prevent a control lever from being moved out of neutral when the vehicle is not being driven in forward or reverse. A typical device will incorporate a hinged plate having a U-shaped cutout arranged at right angles to the hinge pivot point. When the operator wishes to lock a control lever in neutral the U-shaped bracket is flipped over so that the control lever is in the cutout and cannot be moved in a fore and aft plane. One disadvantage of this typical device is that it is usually only held in place by gravity (or a weak spring) hence will be a noise generator, both in the engaged and disengaged position. Also it is possible that it can be vibrated out of engagement if the vehicle is subjected to a violent jostling. This could lead to disasterous results if, for instance, the device became disengaged as the vehicle is being towed and the control lever slipped into gear. The lever restraint provided by this invention is designed to positively lock the control lever in neutral and to minimize the chances of it being inadvertently disengaged.
The prior art also knows of position restraining tightening knobs such as are used in this invention. These knobs are usually used where a limit is imposed on the range of movement of a control rod. The knob is moved along a restraining slot until it is at the desired position and then the knob is tightened and thus provides the lever limit stop. A typical use is found in the position control lever of an agricultural tractor so that the farmer can move a plow depth control lever to a fully raised position when he prepares to make a headland turn with the plow out of the ground, then when the farmer gets the tractor turned around, he simply moves the lever to the stop position and thus will be assured of equal depth plowing from row to row.
This invention uses the knob to provide an easy method of tool-free locking of a pivotable plate in either an engaged or disengaged position. In a disengaged position, a knurled security knob is tightened down to hold the pivotable plate out of engagement with the directional control lever. Also in an engaged position, the security knob is tightened down to hold the directional control rod in a neutral position.
It is amongst the objects of this invention to provide a control lever restraining device that can be maintained in either a disengaged or an engaged position and can be easily moved to an opposite position.
It is also an object of this invention to provide a lever restraint that will have a tendency to be self-engaging upon malfunction of a security knob.
An advantage of this lever restraint is that it is compact enough to be positioned between adjacent levers in a multiple lever embodiment. Furthermore, the device is relatively inexpensive and easy to manufacture.
A great advantage is that the lever restraint will securely control a control lever position when the device is properly secured and conversely will not interupt the lever operation when restraint is not desired.